The broad objective of the proposed research is to elucidate the manner in which fat mobilization is regulated in man. To achieve this objective, we have begun to evaluate, or investigate: 1. Various discrete human pituitary fractions for lipolytic and antilipolytic activity. 2. The significance of adenyl cyclase, 3',5'-cyclic adenosine monophosphate (cyclic AMP), and adrenergic receptor sites in mediating human lipolysis. 3. The interactions of insulin, a potent antilipolytic hormone, with the adenyl cyclase system. 4. The relation of glycolysis to lipolysis. 5. Adipose tissue from a variety of non- human species (including primates, pigs, rabbits, and guinea pigs) - with the goal of finding a suitable animal model for human adipose tissue metabolism. 6. In vivo studies designed to determine if alpha adrenergic sites are present in human fat cells, and, if present, their effect on lipolysis. Among the methods to be employed in these studies are an isolated human adipose tissue cell assay; direct measurement of adenyl cyclase, cyclic AMP, and phosphodiesterase; and electrofocusing to separate fractions of human anterior pituitary glands.